The application does check a few parameters of your Mac to help you learn whether High Sierra will probably work on your Mac.
Be aware that the application is in German, but still it shows red, green or yellow icons for various parameters.

Your Mac must of course meet the minimum requirements from Apple and a few technologies only work if you have required hardware. e.g. HEVC decoding with hardware acceleration needs CPUs supporting it. External graphics adapters need Thunderbolt 3 port and APFS a SSD disk. I hope you see a lot of lights being green.

The application can also identify 32-bit kernel extensions which don't work any more.
Also we can find PPC applications (no longer supported for years) and also warn about 32-bit software, which may need an update for macOS 10.14.

Let me know what you think about it. I hope it helps you to decide whether installing macOS High Sierra makes sense.